class Ex5
  #
  # * *Args*    :
  #   - +a+ -> the length of square side
  # * *Returns* :
  #   - the perimeter of this square
  #

  def square_peri(a)
    return 4 * a
  end
  
  #
  # * *Args*    :
  #   - +a+ -> the length of square side
  # * *Returns* :
  #   - the area of this square
  #
  
  def square_area(a)
    return a * a
  end
  
  #
  # * *Args*    :
  #   - +a+ -> the length of rectangle side
  #   - +b+ -> the length of another rectangle side
  # * *Returns* :
  #   - the perimeter of this rectangle
  #
  
  def rectangle_peri(a, b)
    return (a+b) * 2
  end
  
  #
  # * *Args*    :
  #   - +a+ -> the length of rectangle side
  #   - +b+ -> the length of another rectangle side
  # * *Returns* :
  #   - the area of this rectangble
  #
  
  def rectangble_area(a, b)
    return a * b
  end
  
  #
  # * *Args*    :
  #   - +a+ -> the length of circle radius
  # * *Returns* :
  #   - the perimeter of this rectangble
  #
  
  def circle_peri(a)
    return 2 * Math::PI * a
  end
  
  #
  # * *Args*    :
  #   - +a+ -> the length of circle radius
  # * *Returns* :
  #   - the area of this rectangble
  #
  
  def circle_area(a)
    return Math::PI * a * a
  end
end
